Sheriff Chris Nocco, of Pasco County, Fla., said they are suspects in a high-speed chase in Florida in which at least 20 gunshots were fired at a police car. The officer wasn't hurt.

The siblings' mother, Barbara Bell, pleaded for her children to turn themselves in during an interview with a local news station.

"You've made some bad mistakes, but so far no one has been physically harmed," Bell told WFTS-TV. "The only safe thing, the only right thing, the only good thing -- possible thing to do -- is for you to turn yourselves in."

"I love you," she said.

Below the Zephyrhills, Fla., property where the suspects allegedly spent time living together is a sophisticated bunker that neighbors say might have been the source of illegal activity, MyFoxTampaBay.com reports.

The underground structure is made up of two 40-foot cargo containers buried side-by-side with a manmade hallway leading to the bunker. The structure is outfitted with both electricity and running water.

"They have good minds on them and now they are just putting them to waste," the owner of the property told MyFoxTampaBay.com.

The siblings were involved in a car chase last Tuesday with the Zephyrills Police Department that exceeded 100 mph and ended when at least two occupants in the vehicle fired at the officer.

While one of the bullets struck the police cruiser's tires, the officer was not injured.

Later that day, the siblings were allegedly involved in an armed robbery at a bank in Valdosta, Ga. Officials say the siblings had high-powered weapons that they fired at the ceiling during the robbery.

"I couldn't have imagined that they would be involved in what they are involved in now," Pastor Jon Clanton of Grace Church of Zephyrhills, who used to live next door to the siblings, told MyFoxTampaBay.com.

More details about the trio are emerging as the FBI continues to focus on the search for their whereabouts. On Lee Grace's Flickr site, she describes herself as someone who loves to farm, shoot guys and wreck cars. She says her interests are German engineering, milk and causing mayhem with her siblings.

Officials linked the siblings to the case after finding Ryan's ankle monitor near the scene of the car chase. He had been issued the monitor after being convicted of sending sexually explicit messages to an 11-year-old-girl. Records show he had registered as a sex offender on Monday.

Bell told the Associated Press that Ryan was "unbearably discouraged by the terms of his probation" and said he feared the conviction would prohibit him from seeing his newborn son.

Charges were also pending against Lee Grace in Florida for a hit and run and was previously charged with battery. Stanley had previously been charged with marijuana possession.

Police suspect the siblings are carrying "an arsenal of weapons," after tracing prior background checks run by gun sellers and confirming that Ryan bought an AK-47 assault rifle at a pawn shop two years ago. Authorities say the rifle is similar to the one used in the bank robbery. Similar checks also show Stanley owns guns.

"They pose an immediate threat to any law enforcement that comes into contact with them," said agent Stephen Emmet of the FBI's Atlanta office.

Authorities say all three suspects are known to abuse drugs, are driving a white Subaru Impreza with New York tags stolen from Ryan's girlfriend, and if you have any information on the whereabouts of any one of the Doughertys to please call 9-1-1.